This invention relates generally to harvesting machines of the self-propelled combine type. As is well known to those skilled in the art, the self-propelled combine is commercially available in either a level-land combine or a hillside combine. The level-land combine is supported on a fixed drive axle, and thus when the combine operates over rolling ground, the operative portions of the combine tilt with the contour of the ground. Although the separating and cleaning units of the combine can handle some degree of tilt without a loss in efficiency, if the combine becomes tilted too much, the crop being harvested builds up on the low side of the machine, resulting in poor separating and cleaning action. When this occurs, the material being harvested overloads the sieve and cleaning shoe on the low side of the machine and the efficiency of the separating action is lessened, resulting in excessive crop losses.
There are commercially available attachments for level-land combines that are to be frequently operated on hilly terrain. These side hill attachments are usually shields or deflectors added to the separator unit to prevent the material being harvested from falling to one side of the separator. These devices, however, do not effectively reduce the material buildup on the low side of the machine since the material has already accumulated on the low side by the time it moves to the separator unit. As a result, separating and cleaning action may still be adversely affected when the combine operates on steep side hills. To some degree, the efficiency of the level-land combine can be maintained when it is operated on side hills by reducing the speed of the combine in order to give the material on the low side time to be processed. This has the obvious disadvantage of substantially increasing the operators harvesting time when very often time is critical.
In addition to the level-land combines, there are combines designed to operate on rolling terrain. These hillside combines generally are supported on pivoting axles which adjust to the changing slopes of the ground and thereby automatically maintain the separator and cleaning units level. In these hillside combines, the header assembly automatically conforms to the slope. An example of this type of hillside combine is disclosed in Clifford et al U.S. Pat. No. 2,947,134, dated Aug. 2, 1960 and entitled "Adjustable Header Device for Hillside Combine." The hillside combine operates very efficiently on either level ground or side hills, but because of the necessary mechanism to compensate for hillside operation, these combines are considerably more expensive then the level-land combines. For a farmer who has primarily level ground but who must harvest some of his crop on side hills, the cost of the hillside combine is prohibitive.
There is, therefore, a need for a combine or an attachment for a combine which will allow the combine to be operated on hillsides without materially affecting the efficiency or the speed of the harvesting operation. Such a combine or attachment must also be relatively low in cost and easy to operate and maintain.